in proper operating condition. Orifice meters are used in pipelines where the interface passage needs to be
PART B - METER INSTALLATION AND PROTECTIVE DEVICES
Meter Installation. A typical meter installation would be set up as follows:
DIRECTION OF FLOWFilter separator Strainer Air eliminator Meter.
The strainer is downstream of the filter separator in case you have a ruptured element. The strainer will
catch any fiberglass or filter paper that might get into the meter and cause it to hang up. There is also a
strainer in the system on the suction side of the pump. This would prevent any trash from entering the filter
Line Strainers. Line strainers consist of a metal housing which holds a canister-shaped wire mesh
strainer. The mesh is usually 25 mesh or more.
Uses. Line strainers are used in the suction side of pumps and on the inlet side of meters preventing
debris from entering the pump and damaging the impeller or meter.
Maintenance. Line strainers should be inspected and cleaned on a periodic basis (recommended at once
a week). The gaskets are checked for damage, cleaned, and returned to use.
Air Eliminators. Air eliminators are placed in the line on the intake side of the meters. It consists of a
cylinder usually 14 inches to 20 inches in diameter, containing baffles that are designed to force the flow of
fuel to the bottom of the cylinder and to force air to the top. On the top of the cylinder is a diaphragm float-
activated valve. The float holds the valve open, allowing air and vapors to escape to the atmosphere; when
all air is removed, the float rises in the product and closes the valve.
The flange gaskets should be checked daily for leaks. The diaphragm valve should be checked daily to
ensure it is working properly or to be replaced if needed. Remove any rust and paint.
PART C - PROVING DEVICES
Prover tanks. There are several types of provers available for proving meters. They are primarily tanks
or piping of a known volume. When they are filled, the known volume is compared to the metered
volume (unknown). Prover tanks normally range in size up to 600 gallon capacity.
Five gallon prover. The 5-gallon prover is used for proving small meters on tank trucks and at service
station type installations.
Mechanical displacement provers. These provers have a calibrated continuous loop and a spheroid.
The sphere displaces a known volume from the number one sensor to the number two sensor, and the
amount displaced is compared to the meter reading. You will find this kind of meter in fixed installations,
or they may be trailer-mounted.
Open volumetric prover. Open provers can be trailer-mounted or in a fixed installation. They consist of
the tank, the neck of the prover, a splash dome, overlapping site gage glasses, and a gage glass scale in
the neck of the prover. Thermometers are at the top and bottom. Provers are used in any installation
where you have to calibrate meters in pipelines, loading docks, and dispensing areas. The maintenance
of meters is very limited. Check for dents or distortions, and make sure the sight gages are in good
working order. Make sure the thermometers are certified.
PART D - VERIFICATION REQUIREMENTS
Meters must be verified based on the following factors:
Size of Meters (GPM)
Total Gallons Measured
600 and over
Meters will be calibrated at least every 12 months or whenever the meter is suspect, whichever comes first.
The meter must be within .0025 (1/4 gallon) for every 100 gallons registered by the master meter. If the